Molded knob assembly



y 28, 1940- w; c. BRUCKMAN 2,202,371

MOLDED KNOB ASSEMBLY Filed Nov. :50, 1938 Fla- 5 WITNESS 5: ,3 I INVENTOR 7f W n. G W- C. Blemmvclwmd.

5. H. FIG. 6- BY ATTORN Patented May 28, 1940 MOLDED KNOB ASSEMBLY William 0. Bruckman, Mansfield, Ohio, mam

to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa, a corporation of Pennsylvania Application November 30, 1938,.Serial No. 243,277

9 Claims.

My invention relates to a molded knob assembly, that is, an assembly for mounting a molded actuating knob on a shaft. Such a knob may be used, for example, to actuate the adjusting shaft 5 of a thermostat to adjust the temperature setting of the thermostat. V An object of my invention is to provide an improved assembly of the character set forth.

Another object of the invention is to provide an 10 assembly that may be manufactured at low cost.

A further object is to provide a knob assembly having a colored, translucent dial and which will withstand high temperatures of the shaft on which the knob is mounted.

These and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawing forming a part of this application, in which:

Fig. 1 is a front elevation of a knob assembly incorporating my invention;

Fig. 2 is a horizontal sectional the line II-II of Fig. 1;

Fig. 3 is a sectional view of the knob;

Fig. 4 is a rear elevation of the knob;

Fig. 5 is a sectional view similar to Fig. 2 showing a modified construction; and,

Fig. 6 is an elevational view of an insert used in both assemblies.

Referring to the drawing in detail, I show a rotatable shaft Iii which is used, for example, to adjust the temperature setting of a thermostat (not shown). A molded knob II is attached to one end of the shaft ill for rotatably actuating 35 the same. Heretofore, an expensive insert, molded in the knob, was employed for mounting the knob on the shaft'and for retaining the same against relative rotation. In the assembly comprising my invention, such a molded insert is not 40 required.

The knob ll comprises a relatively fiat handle portion l2 and a circular or disc portion ii. .In the illustrated embodiment, there is included a translucent plate or dial ll whose marginal por- 45 tion projects beyond the periphery of the disc ill view taken on portion i3 and bears indicia indicating the temperature to which the thermostat is adjusted. The plate H is fixed against rotation relative to the knob l I by means of circular bosses i5 formed 50 thereon and recess portions 16 formed in the knob ll, said bosses being received and closely fitted in said recess portions. The plate. Il may be secured to the knob by drive screws I'I extending through openings in the bosses l5.

The assembly includes an insert 55 member l 8,

shown in Fig. 6, which may be a simple stamping. The insert member I8 is arranged to be interlocked against rotation relative to the knob II, and in the illustrated embodiment it has a square periphery. The knob ii is formed with. a recess portion IS on the back thereof which closely engages two opposlte sides and the four corners of the insert member l8.

The insert member I8 is formed with a shaft opening 20, through which the shaft l extends as shown in Fig. 2. I The edge of the opening 20 and the end portion of the shaft extended therethrough are finely knurled longitudinally of the shaft so as to permit the insert to slide longitudinally on the end portion of the shaft and to interlock the insert member and the shaft against relative rotation. The knob I I is formed with an opening 2i into which the end of the shaft extends, and an opening 22, disposed tangentially of the opening 2|, is also formed'therein. The shaft is formed with an annular groove 23, and a self-tapping screw 24 is inserted in the opening 22 to engage the groove 23 and retain the knob II on the shaft it against movement longitudinally of the shaft.

The plate I4 is also formed with an opening 25 through which the shaft I0 extends, and as shown in Fig. 2, there is a clearance between the shaft and the edge of the opening. The purpose of this clearance is to prevent overheating of the plate It, as when the assembly is used in connection with the thermostat of an electric roaster, in which casethe shaft Ill maybe heated to a considerable extent. The knurling on the shaft I0 may also be disposed so as to hold the insert member IS in spaced relation to the plate It, as shown on Fig. 2, to prevent transmission of heat.

To assemble the parts, the insert member i8 is first inserted in the recess portion l9, and the plate I4 is then positioned against the back of the knob, the bosses l being inserted in the recess portions. IS. The drive screws H are then driven in to fasten the plate It to the knob. The knob and the shaft ill are positioned in proper' angular relation, whereupon the end of the shaft is inserted through. the opening 25 in the plate It and the knurled opening 20 in the insert member l8, and into the opening M in the knob II. The screw 24 is then inserted to complete the assembly.

The insert member [8 being interlocked with the shaft against relative rotation by, the knurling, and the knob Ii being interlocked with the insert member against relative rotation by the rectangular form thereof, it will be apparent that the shaft 10 may be rotated by actuating the knob The purpose of finely knurling the end of the shaft l and the opening 20 in the insert member I8 is to enable the knob and dial to be accurate ly positioned in proper angular relation to the shaft l0 when mounting the same thereon, inasmuch as it is not possible to predetermine the position of the shaft I0. I

The assembly described above is particularly suitable where a colored, translucent dial is desired. Suitable materials for such 'a dial will not stand the high temperatures encountered in an electric roaster. With the two-piece assembly described above, the knob itself can be made of a diflerent temperature resisting material, for example, a. suitable resinous condensation product, such as Bakelite or Micarta. By providing clearance between the shaft and the opening of the dial, the transmission of heat from the shaft f to the dial is sufficiently retarded, so that a satisfactory assembly is provided.

In Fig. I show a modified form of assembly in which the shaft 3|, which is to be actuated, is not subjected to high-temperature. In this case, it is not necessary to provide clearance between the shaft and the opening 24 in the plate. The shaft is formed with a shoulder 32, the end portion of the shaft being of lesser diameter than the remainder of the shaft. In this case, the plate Ila is held between the shoulder 32 and the knob II, it not being necessary to provide the drive screws l1.

The shou1fler32 may also be used when the plate Ma. is not used. In this case the insert member l8 may be held between the shoulder 32 and the knob H. Alternately, it may be held between the knob I I and the end of the knurling.

Further modifications may be madein my molded knob assembly invention without departing from the spirit and scope thereof and I, therefore, desire that only such limitations shall be imposed thereon as are indicated in the appended claims.

What I claim is:

1. A knob and shaft assembly comprising a shaft, a knob mounted thereon, a key member separate from said knob for preventing relative rotation between said knob and said shaft, said knob having a recess in which said key member is disposed, said recess and said key member being formed to prevent relative rotation therebetween, said knob and said key member having aligned shaft openings in which said shaft extends, the edge of the shaft opening in said key member and the portion of the shaft extending through said last-mentioned opening being formed to permit relative movement between said shaft and said key member longitudinally of the shaft and to prevent relative rotation therebetween, means independent of said shaft for retaining said key member in said recess in said knob, and means acting directly between said knob and said shaft for restraining relative movement therebetween longitudinally of said shaft.

2. A knob and shaft assembly comprising a shaft, a knob mounted thereon, a key member I I separate from said knob for preventing relative rotation between said knob and said shaft, said knob having a recess in which said key member is disposed, said recess and said key member being formed to prevent relative rotation therebetween,

said knob and said key member having aligned shaft openings in which said shaft extends, the edge of the shaft opening in said key member ment between said shaft and said key member longitudinally of the shaft and to prevent relative rotation therebetween, means independent of said shaft for retaining said key member in said recess in said knob, and means acting directly between said knob and said shaft for restraining relative movement therebetween longitudinally of said shaft. I I 3. A knob and shaft assembly comprising a shaft, and a knob, a plate member and a key member having aligned shaft openings in which said shaft extends, said plate member interlocking with said knob to prevent relative rotation therebetween and having a peripheral portion projecting beyond the knob, said key member being disposed between said knob and said plate member, said knob and said key member being formed to prevent relative rotation therebetween, the shaft opening in said key member-and the portion of the shaft extending therein being formed to prevent relative rotation therebetween, said shaft having a recess in a portion thereof disposed within said knob, and means extending in said knob and in said recess to prevent relative longitudinal movement between said knob and said shaft.

4. A knob and shaft assembly as set forth in claim 3, wherein the portion of the plate member adjacent the shaft opening is disposed in spaced relation to said shaft.

5. A knob and shaft assembly as set forth in claim 3, wherein the portion of the plate member adjacent the shaft opening is disposed in spaced relation to said shaft and to said key being formed with a recess or recesses in which 7 said key member and said boss are received, said recess or recesses, said key member and said boss being formed to prevent relative rotation therebetween, the edge of the shaft opening in the key member and the portion of the shaft extending therethrough being formed to prevent relative rotation therebetween, means for securing said plate member to said knob, and means for restraining relative movement between said knob, said plate member, said key member and said shaft.

7. A knob and shaft assembly comprising a shaft having a shoulder formed thereon and an .end portion of reduced diameter, a knob, a key member separate from the knob, and a plate member having aligned shaft openings in which said end portion of the shaft extends, said plate member being retained between said shoulder and the ,knob and having a peripheral portion extending beyond said knob, said plate member and said key member being formed to prevent rotation relative to the knob, the shaft opening in the key member and the portion of the shaft extending therein being formed to prevent relative rotation therebetween, and means engaging said shaft and said knob for preventing relative movement therebetween longitudinally of the shaft.

8. A knob and shaft assembly comprising a shaft, anda knob, a plate member and a key member having aligned shaft openings in which said shaft extends, said plate member interlocking with said knob to prevent relative rotation therebetween and having a peripheral portion projecting beyond the knob, said key member being disposed between said knob andsaid plate member, said knob and said key member being formed to prevent relative rotation therebetween,

the shaft opening in said key member and the portion of the shaft extending therein being formed to prevent relative rotation therebetween, and means for restraining relative movement between said knob and said shaft longitudinally of said shaft.

9. A knob and shaft assembly comprising a shaft having a shoulder formed thereon and an end portion of reduoeddiameter, a knob, a key member separate from the knob, and a plate member having aligned shaft openings in which said end portion of the shaft extends, said plate member being retained between said shoulder and the knob, said plate member and said key member being formed to prevent rotation relative to the knob, the shaft opening in the key member and. the portion of the shaft extending therein being formed to prevent relative rotation therebetween, and means engaging said shaft and said knob for preventing relative movement therebetween longitudinally of the shaft.

WILLIAM C. BRUCKMAN. 

